Grinding disc



W. KOHN lll Dec. 25, 1962 GRINDING DISC Filed Oct. 11, 1960 mvcmon: WILLIAM KOHN HI United States Patent 3,069,817 GRINDING DIS William Kohn Ill, Chalfont, Pa., assignor to Sim-ends Abrasive Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Oct. 11, 1960, Ser. No. 61,959 3 Claims. (Cl. 51-409) The present invention relates to new and useful improvements in means for mounting abrasive bodies and more particularly to means for mounting abrasive bodies such as grinding discs and the like on the face plate or chuck of a grinding machine.

A primary object of the present invention is to provide novel mounting means for an abrasive body or the like which provides a more rigid and stronger unit than presently existing devices of this type and which may be readily attached to any conventional face plate or chuck of a grinding machine.

Another object of the present invention is to provide a novel abrasive body or the like having mounting means rigidly secured thereto which are accurately positioned relative to the central axis of the abrasive body and which will permit the abrasive body to be readily and accurately centered on the face plate or chuck of a grinder.

A further object of the present invention is to provide novel apparatus of the type described having the features and characteristics set forth which may be manufactured easily and cheaply and is entirely efficient and effective in operation and use.

These and other obiects of the present invention and various features and details of the operation and construction thereof are hereinafter more fully set forth and d..- scribed with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary side elevational View of a conventional grinding machine having an abrasive made in accordance with the present invention mounted there- FIG. 2 is an enlarged transversed sectional View illustrating an abrasive and mounting means made in accordance with the present invention secured to a conventional face plate;

FIG. 3 is a sectional view taken along line I-3, FIG. 1, illustrating the positioning of the mounting means for the abrasive body;

FIG. 4 is an enlarged fragmentary sectional view taken on line 4-4, FIG. 3, illustrating one form of the mounting means of the present invention; and

FIG. 5 is a fragmentary transverse sectional View illustrating a modified form of mounting means of the present invention.

Referring more specifically to the drawings and particularly to FIG. 1 thereof, reference numeral designates generally a grinding disc made in accordance with the present invention which is mounted on the face plate 11 of a conventional grinder 12 and held in position on the face plate by means of a plurality of bolts 13 or the like.

As illustrated in FIG. 2, the grinding disc 10 may comprise an abrasive body 14 and a backing plate 15 which is bonded or otherwise secured to the abrasive body 14. The abrasive body 14 may comprise any conventional abrasive grain in any conventional binder such as organic or vitreous binder. Additionally, the abrasive body 14 may be of any desired shape, for example, it may be in the form of a flat cylindrical body or disc as shown in drawings wherein grinding takes place on the forward surface of the body or the abrasive body may have any desired predetermined irregular shape in order to accomplish any desired special grinding operation. The backing plate 15 is in the form of a flat annulus having an external 3,069,817 Patented Dec. 25, 1962 peripheral surface which closely conforms to the peripheral surface of the abrasive body and a relatively large central opening 16 therein. This backing plate may be formed of any desired material such as a metal or plastic and, for example, may be precoated with a resin or an adhesive as illustrated at 17 to securely bond the backing plate to the adhesive body.

An important feature of the present invention is the provision of fastening means which are secured to both the backing plate and the abrasive body to permit the abrasive body to be readily secured to the face plate or chuck of a grinding machine. To accomplish this, a plurality of uniformly spaced insert members 18, formed for example as illustrated in FIG. 2, are provided which are secured to the backing plate and embedded within and secured to the abrasive body. Additionally, the insert member is provided with means to permit the ready and rapid attachment of the abrasive body and backing plate to the face plate or chuck of the grinder. The insert member 18 illustrated in the embodiment of FIGS. 2 and 4 comprises a circular bushing having a central threaded opening 21 therein permitting a bolt 22 to be inserted through an opening 23 in the face plate and threadedly received in the opening 21 of the insert member to thereby secure the abrasive body and backing plate to the face plate. In this embodiment of the present invention, the external peripheral surface of the insert member 18 is knurled or otherwise roughened as indicated at 24 and the bushing is inserted directly into the abrasive body 1% while the abrasive body is being formed or molded. To prevent the material of the abrasive body from entering the central opening 21 of the insert member a small cap or cover plate 25 is provided which is positioned over the inner end of the insert member during the molding operation. With this construction the insert member is securely embedded within the abrasive body and will not become loose and detached therefrom.

The outer end of the insert member 18 is positioned so that it extends into a flared opening 26 provided in the backing plate 15 and is peened over or otherwise deformed to conform to the shape of the opening 26 and become firmly anchored to the backing plate 15. With this construction, the insert member 18 may be firmly secured to even an unreinforced abrasive body and permit a rigid attachment of the abrasive body to a face plate or chuck of the grinding machine.

This above described construction is particularly suitable for use with wheels such as organic bonded wheels which are initially molded and then placed in an oven and cured at a relatively low temperature. To assemble the above wheel, the various knurled inserts are first secured to the plate 15 and the plate 15 is inserted into a mold with the knurled inserts projecting into the mold cavity. This caps 25 are thereafter placed over the tops of the knurled inserts and the backing plate is precoated with a resin or adhesive as illustrated at 17. Thereafter the abrasive body is molded directly about the knurled inserts providing an abrasive wheel in which the backing plate is permanently secured to the wheel. With this construction the knurled inserts are accurately positioned within the abrasive wheel and distortions of the abrasive body during the curing operation will not affect the relative position of the inserts.

A modified form of the construction of the present invention is illustrated in FIG. 5 of the drawings wherein a recess 27 is provided in the abrasive body 14 with the knurled insert member 18 being secured Within the recess 27 by means of a cement or bonding material. This form is particularly designed for use with a vitreous type of abrasive wheel which normally is cured at temperatures that would deleteriously affect the material of the backing plate. In this embodiment the recesses or openings 27 in the abrasive body extend partially into the abrasive body from the rear face thereof and are preferably formed in the abrasive body when the abrasive body is initially molded. After the molding operation is completed, the insert members 18, which previously have been secured to the backing plate as described above, are secured within the recesses by means of a thin layer of bonding material or cement 28 which directly bonds the insert memhers and backing plate to the abrasive body. If desired, a 'cap 25 may be positioned over the knurled insert before the insert is inserted into the opening 27 to prevent the bonding material from entering the central opening of the knurled insert.

From the foregoing it will be observed that the present invention provides novel mounting means for an abrasive body and the like which provides a, more rigid and stronger unit than presently existing devices of this type and which permits the abrasive body to be readily attached to any conventional face plate or chuck of a grinding machine.

While particular embodiments of the present invention have been illustrated and described herein, it is not intended to limit the invention to such a disclosure and changes and modifications may be incorporated and embodied therein within the scope of the following claims.

I claim:

1. A grinding disc or the like comprising an abrasive body having a planar circular rear face, a planar annular backing plate formed of rigid material having an external diameter substantially equal to the external diameter of the abrasive body, means adhesively bonding said annular ring to the rear face of said abrasive body, means defining a plurality of openings extending through said annular ring and spaced uniformly about said annular ring and flared outwardly away from said abrasive body, a plurality of in-' ternally threaded inserts corresponding in number to said openings in said annular ring and projecting into said abrasive body, said inserts comprising a cylindrical body portion of greater diameter than the diameter of said openings in engagement with the face of said annular ring adjacent said abrasive body and received entirely within said abrasive body and an outer end portion received within said annular ring opening and flared outwardly to conform to the shape of the said annular ring opening and securely anchoring said insert to said annular ring, and means securing said insert body portion to said abrasive body.

2. Apparatus in accordance with claim 1 wherein the means securing said insert to said abrasive body comprises a layer of adhesive intermediate the peripheral surface of said insert body portion and said abrasive body bonding said insert body portion to said abrasive body.

3. Apparatus in accordance with claim 1 wherein the means securing said insert to said abrasive body comprises a knurled outer surface on said insert body portion mechanically interlocked with said abrasive body.

References Cited in the file of this patent UNITED STATES PATENTS 1,856,321 Doermann May 3, 1932 1,912,070 Doermann May 30, 1933 2,080,156 Wolf May 11, 1937 2,118,409 Loewy May 24, 1938 2,806,331 Hoye Sept. 17, 1957 2 ,836,017 Tyge May 27, 1958 

